The present invention relates to a photometric system applied to an image pick-up device such as a still camera, a moving camera, a television camera, an industrial television camera and the like.
In case of photographing an object by a camera, it has often occurred that the object becomes too dark with rear light or the object becomes too bright when photographing at night. As a photometric system for eliminating such conventional disadvantage, Japanese Patent Laid-open No. 129,221/75 discloses such system that provision is made of a light receiver having a number of light-receiving elements consisting of an image sensor such as CCD (charge coupled device) or the like for receiving light present on the whole surface of the field of an object, thereby deriving a luminance signal of a previously selected necessary photometric portion among luminance signals corresponding to positions of an object successively obtained from the light receiver and carrying out spot photometry. Such photometric system, however, requires to designate a photometric portion, so that its operation is troublesome, and it is necessary to derive a luminance signal corresponding to respective photometric portions, so that its circuit construction becomes complicated and large. In case of photographing a moving object, it is difficult to correspond the object to a desired photometric portion, so that it is almost impossible to carry out precise spot photometry.